I check the option share the Whole site while creating the template and when i go and create a new site and selected that template. it should clone the same DB which it never did?

any info?

Share "whole website" does NOT clone the website.
You are using the same DB with the same table prefix.
The only thing that you can do in this case is deploy the website into another directory and for example change the layout of the template selected. You can NOT change the template default as this will affect the other website. Just change some parameters in the templates configuration or modify the css, ....

This is not frequently used.
For example, it may be used by companies that want to have as many identical websites than they have dealers and just want to change very few information like the "contact" in the bottom of the page or things like that.

ok but what i am looking for is following:

we have setup the main website.

joomla

now, we want to have every area in NY to have their own website.

brooklyn.joomla.com
manhattan.joomla.com
queens.joomla.com

all of these sites will be totally different in accordance with data and modules but at the starting we need them to be same as main joomla.com for now so that we can start editing.

thanks.

No problem.
Create a "generic" website that will be used as template to create the other one.
For example nystate.joomla.com
once you have this NYstate.joomla.com you could build your brooklyn, manhattan, queens subdomains based on the nystate website.

So start to create the NYstate website.
After create a JMS templates rule (ie. create_cities) that will replicate the "nystate" one.
Finally create a slave site using the rule "create_cities". You could use the {site_id} for the city value (brooklyn, manhattan, ....)

I love you